1. Field of the Invention
The present invention relates generally to the field of engines which convert heat into mechanical energy. More specifically the present invention relates to a thermal engine such as for powering a vehicle, including a cylinder and a piston having a piston head and a piston crank and an insulated thermal battery including at least a thermal mass such as a metal block for storing and retaining heat to cause expansion fluid to expand inside the a cylinder expansion chamber between the cylinder head and the piston head to drive a crankshaft.
In its most basic form, as mentioned above generally, the thermal engine incorporates several conventional engine elements including engine valve block cover sealingly mated to an engine valve block sealingly mated to an engine block sealingly mated to an oil sump. The engine block having a cylinder chamber within which a piston head is slidably and sealingly retained to form a variable volume cylinder expansion chamber between a piston head and the engine valve block, said engine valve block having a intake valve port with a intake valve and having an exhaust valve port with an exhaust valve; the intake valve port fluidly connected to an intake chamber within the valve cover for receiving expanded fluid from the thermal battery, said exhaust valve port fluidly connected to an exhaust chamber for removal of exhausted expanded fluid; a crankshaft mechanically linked to the piston head opposite the engine valve block by a piston crank, a valve operating means comprising a cam shaft and cams mounted thereon, said cam shaft driven by the torque of a drive shaft; an engine starting means connected to drive shaft; a thermal battery consisting of a contiguous thermal battery case divided into two separate fluid chambers by a thermal mass for storing heat energy, the first chamber consisting of a thermal battery expansion chamber in fluid communication with the intake chamber and the expansion fluid tank, an expansion fluid pump for delivering expansion fluid from the expansion fluid tank into a thermal battery, the thermal battery consisting of a contiguous thermal battery case divided into two separate fluid chambers by a thermal mass for storing heat energy, the first chamber consisting of a thermal battery expansion chamber in fluid communication with the intake chamber and the second chamber consisting of a hermetically sealed thermal battery vacuum chamber surrounding most of the thermal mass, said thermal battery expansion chamber having thermal mass expansion fluid passageways within said thermal mass for accepting expansion fluid from the expansion fluid pump to uniformly heat and expand expansion fluid from a liquid phase to an expanded fluid in the vapor phase within the thermal mass, the thermal mass expansion fluid passageways fluidly connected to transmit and accumulate pressurized expanded fluid vapor into the thermal battery expansion chamber and then into the intake chamber so that when the engine starting means turns the drive shaft, the expansion fluid pump delivers a quantity of expansion fluid into the thermal mass expansion fluid passageways causing expansion fluid to expand into a vapor and become expanded fluid, and when the piston head is at top dead center of the cylinder chamber a cam opens the intake valve and expanded fluid vapor is passed through the intake valve port into the cylinder expansion chamber to generate pressure and drive the piston head from top dead center to bottom dead center, the piston head motion generating a force transmitted by the piston crank to turn the crankshaft and generate mechanical power using the thermodynamic potential of the expanded fluid vapor, so that when the piston head is at bottom dead center the drive force generated on the drive shaft causes a cam to close the intake valve and a cam to open the exhaust valve and cause expanded fluid vapor to exit through exhaust valve port into the exhaust chamber for removal of exhaust expanded fluid as the piston head rises to top dead center passing expanded fluid vapor into a radiator to cool and condense the expanded fluid vapor back into expansion fluid and to advantageously generate a negative vapor pressure to assist and pull the piston head back to top dead center to repeat the cycle; a flow check valve on the radiator output prevents back flow of condensate to maintain a negative pressure; an expansion fluid tank to receive condensed expansion fluid from the radiator, an expansion fluid pump for pumping expansion fluid from the expansion fluid tank back into the thermal mass expansion fluid passageways to repeat the process.
The valve operating means preferably includes a cam shaft and push rods exhaust valve and intake valve riding on cams along the cam shaft which forces them to open and close against a cam spring compression force in a conventional fashion. A flywheel is attached to the drive shaft connected to one end of the crankshaft preferably extends out of the crankcase through a shaft port to transmit the thermal engine power in the form of torque to any desired mechanical load such as the pump.
In the closed cycle format of the invention, the expansion fluid delivery means preferably is an expansion fluid pump or simply gravity in the case of a small engine. In the case of an open cycle format of the present invention, the expansion fluid delivery means alternatively consists of pressurizing the expansion fluid tank to pump out expansion fluid into the thermal mass expansion fluid passageways by pressure. In the closed cycle format, no expansion fluid is lost and the same quantity of expansion fluid remains in the engine cycle in vapor and liquid phase and is reused over and over again by means of condensation. In the case of an open cycle format the expanded fluid is exhausted into the atmosphere without the need for a radiator.
In general operation of the closed cycle engine, heat is generated and stored in the thermal mass by one of two means. The first means is by passing electric current through resistive heating elements embedded in the thermal mass for a period of time and the second alternative means is by imposing an electromagnetic induction heating means on the thermal mass for a period of time. The thermal engine is started by rotating a drive shaft connected to turn a crankshaft. The crankshaft turns an expansion fluid pump which pumps a quantity of expansion fluid from an expansion fluid tank through a flow regulator into the thermal mass expansion fluid passageways. The flow regulator allows only the prescribed amount of expansion fluid to pass into the thermal mass expansion fluid passageways and the heat stored in the thermal mass causes the expansion fluid to expand by a phase change into expanded fluid to generate pressure in the intake chamber. The turning of the crankshaft causes the piston head to move and when it rises to top dead center, the cam shaft is positioned to cause the cam to push the intake valve to an open position while causing the exhaust valve to go into a closed position. The pressurized expanded fluid in the intake chamber rushes through intake valve port into the cylinder expansion chamber and pushes the piston head to bottom dead center position turning the crankshaft and thereby rotating the cam shaft to cause the cam to close the intake valve and also open the exhaust valve causing the piston head to return to top dead center position using the momentum stored in a flywheel and allowing the expanded fluid to exit the cylinder expansion chamber into the exhaust chamber through exhaust valve port. The expanded fluid is either transported through an exhaust tube to the radiator in the closed cycle format of the invention, or it is expelled to atmosphere in the open cycle format of the invention through the exhaust tube.
In the closed format of the invention, the radiator cools the expanded fluid vapor back into expansion fluid and a check valve at the end of the exhaust tube generates a vacuum within the exhaust chamber to increase the power of the thermal engine since when the exhaust valve port opens the negative pressure in the cylinder expansion chamber will, in addition to the energy stored in the flywheel, cause the piston head to rapidly return by negative pressure to top dead center position. This adds more power to the thermal engine since the invention essentially teaches the use of expansion fluid in both its pressurized vapor expanded fluid form and its vacuum condensate state to push and return the piston head from top dead center position to bottom dead center position and back to top dead center position. This vacuum assistance is possible in both the open cycle format and the closed cycle format if the exhausted expanded fluid is passed through a long enough exhaust tube before being exhausted to atmosphere. In such a case, the rapid cooling of the expanded fluid in the exhaust tube causes the expanded fluid to undergo a phase change from the vapor phase to the liquid phase and such rapid condensation results in a vacuum being generated momentarily in the exhaust chamber. Thus, by adjusting the length of the exhaust tube, it is possible to regulate the timing of the vacuum formed with the motion of the piston head as moves from top dead position center to bottom dead center position and then back to top dead center position.
At close to bottom dead center the turning of the crankshaft, the momentum stored in the flywheel, and the negative pressure of vapor condensation causes the piston head to rapidly move back towards top dead center to repeat the cycle and to rotate the cam shaft to a position that causes the cam to make the intake valve close while causing the exhaust valve to open. In a closed cycle format of the invention, the pressurized expanded fluid in the cylinder expansion chamber is pushed through exhaust valve port into the exhaust chamber allowing the expanded fluid to exit the cylinder expansion chamber and through the exhaust tube into the radiator. Alternatively the expanded fluid can exit the cylinder expansion chamber through the exhaust tube to bypass the radiator and be expelled directly to atmosphere. The piston head freely returns to top dead center by the continued angular momentum, the rotation of the crankshaft and flywheel and allowing the remaining elements of the expanded fluid out of the cylinder into the exhaust chamber to cool either in the exhaust tube or in the radiator to and generate a negative pressure of vapor condensation so that the cycle can continuously repeat until stopped. To stop the cycle, the flow regulator is simply closed off to stop the flow of expansion fluid into the thermal battery.
2. Description of the Prior Art
So-called gas and combustible fluid engines are known that can operate with different types of fuels and are based on certain thermodynamic principles, such as the Diesel, Carnot, Rankine, and Otto cycles. In combustion engines an air-fuel mixture is compressed and then ignited. The compression results in an expansion of gases within the cylinder chamber, pushing a piston slidably retained within the cylinder in a repeated cycle to turn a crank shaft and so to generate mechanical power from the fuel. The current prior art engines therefore rely on combustible fuels that cause global pollution and health associated problems. In an effort to reduce the pollution and dependence on fossil fuels, several types of engines have been invented including electrically powered vehicles which rely on the storage of electric power in batteries.
While these vehicles are of current interest, a growing concern about the disposal of chemical batteries and the efficient global transformation of these new technologies to replace existing technologies has emerged. What is needed is a thermal engine design which adopts a philosophy of replacing or assisting existing technologies such as fossil fuel combustion engines and electric battery powered vehicles. Such a thermal engine as described by the present invention uses thermally generated power in a closed or open thermodynamic cycle to generate power without pollution. It also can be used in conjunction with conventional engines to improve their efficiencies without substantial change to current engine manufacturing technology.
It is thus an object of the present invention to provide an engine which can be operated with non-combustible expansion fluids which do not combust and which uses a phase change to expand a fluid from a liquid phase to a vapor phase and generate power thereby achieve a high degree of efficiency during operation. An engine of this kind, in accordance with the invention, can be optimized by its geometry through maximizing the thermal mass and minimizing the surface area of the thermal battery for storing a maximum amount of thermal energy in the form of a direct heat. Without limiting the scope of the invention, however, the preferred mode of operation is in a pure thermal mode where the thermal battery is simply a thermal mass consisting of a ceramic composite and alternatively metal allows and molten salts that have high thermal storage capacity.
It is another object of the present invention to provide and thermal battery which can be used in conjunction with a molten electrolytic salt contained within the battery as a thermal mass to store heat.
It is still another object of the present invention to provide an engine in which pressure generated when vapor expands from a liquid state can then be used as a vapor powered engine, whereof, a liquid such as water is injected into the thermal mass of the engine to generate pressurized steam as an expanded fluid to generate power.
Advantageously, much more energy can be stored in such a thermal battery than in a conventional electric battery of the same weight since the thermal storage capacity of a regular chemical battery far exceeds its electric storage energy. It is in fact the preferred means that Nature has chosen to store energy in stars and gravitating bodies.
Advantageously, such a thermal battery powered engine can be equipped with an expansion fluid condensation radiator to generate addition negative pressure within the cylinder during the exhaust cycle to increase the power of the engine.
It is a further objective of the present invention to disclose a thermal engine that is powered by a thermal battery causing a phase change in an expansion fluid from a liquid phase to a vapor phase.
It is a further objective of the present invention to disclose a thermal engine that can be operated in a closed cycle without any exhaust and that reuses a fixed amount of expansion fluid in a closed cycle that undergoes a phase change from a liquid to a vapor to do thermodynamic work and then back to a liquid phase to be reused in a continuous fashion.
It is a further objective of the present invention to disclose a thermal engine that can be operated in an open cycle that uses an indefinite amount of water as an expansion fluid that undergoes a phase change to steam to do thermodynamic work and that can be exhausted to atmosphere without causing pollution.
It is a further objective of the present invention to disclose a thermal engine that can be recharged by means of electric thermal heating means over a period of time to store energy in a thermal battery.
It is a further objective of the present invention to disclose a thermal engine that can be rapidly recharged by means of electromagnetic induction heating over a period of time to store energy in a thermal battery. Advantageously such an electromagnetic induction charging system can be non-invasive and thus in the case when the thermal engine is used in a vehicle, the vehicle would simply slowly pass over such an inductor placed alongside or under the road and gets charged without having to stop.
It is finally an object of the present invention to provide an engine which is highly efficient and easy to operate and environmentally friendly. Advantageously the thermal battery can be made from recyclable materials that have no adverse environmental effects.
Advantageously, unlike electric batteries whose potential deteriorates with the number of charges, the thermal battery can be recharged with heat a large number of times without reducing its capacity to store heat energy, and without deterioration. Further, the thermal battery is environmentally safe and can be reused to manufacture new items by recycling its material without any consequences to the environment.
Further, in an open cycle embodiment of the present invention, the exhaust of the engine using a thermal battery can be pure water or steam. In a closed cycle format embodiment of the present invention, any refrigerant fluid that has suitable thermodynamic properties can be used since the exhausted condensate of the expanded fluid is recaptured from the engine and recycled, and such an engine would need very little expansion fluid to operate in a closed system and no emissions would result.